UDP-galactose pyrophosphorylase

Beginning in adolescence, UDP-galactose is produced in a reaction catalyzed by UDP-galactose pyrophosphorylase ... 

Three different enzymes may catalyze the formation of UDP-galactose (1) UDP-glucose 4-epimerase (UDP-galactose 4-epimerase) (2) UDP-galactose pyrophosphorylase and (3) galactose 1-phosphate uridyl... 

Fig. 14. Salvage pathways of nucleotide sugars. L-fucose (11), (3-L-fucose-l-phosphate (12), GDP-p-L-fucose (13), A fucokinase (EC 2.7.1.52), B GDP-Fuc pyrophosphorylase (EC 2.7.7.30). D-galactose (14), a-D-galactose-l-phosphate (15), UDP-a-D-galactose (16), C galactokinase (EC 2.7.1.6), D UDP-Gal pyrophosphorylase. IV-acetyl-D-galactosamine (17), Al-acetyl-a-D-galactosamine-l-phosphate (18), UDP-lV-acetyl-a-D-galactosamine (19), E IV-acetyl-galactosamine kinase (EC 2.7.1. ), F UDP-GalNAc pyrophosphorylase (EC 2.7.7. )...

Scheme 4.23 The use of glycosyl transferases in combination with in situ co-factor regeneration. E —galactosyl tranferase E2 — pyruvate kinase E3 = UDP-Glc-pyrophosphorylase E4 = galactose-1-phosphate uridyl transferase E5 = galactokinase.

Two pairs of chemically matched reactions exemplify the importance of shared binding sites in the evolution of double-displacement pathways. They are the reactions catalyzed by UDP-glucose pyrophosphorylase (inversion) [74] and galactose- -P uridylyltransferase (retention) [21], which catalyze Reactions 21 and 22,... 

Fig. 2. Galactosylation with galactosyltransferase and integrated cofactor regeneration. (Enzymes i phosphoglucomutase, ii UDP-glucose-pyrophosphorylase, iii inorganic pyrophosphorylase, ivUDP-galactose-4-epimerase, V galactosyltransferase, vi pyruvate kinase, vii hexokinase) [31]...

Ev pi,4-galactosyltransferase Eg pyruvate kinase E3 UDP-GIc pyrophosphorylase E4 Galactose-1-phosphate uridyltransferase E5 galactokinase... 

Scheme 20 Multistep enzymatic preparation of UDP-galactose in the flow-through mode. GalK (galactokinase EC2.7.7.6), GalT (galactose-1-phosphate uridylyl transferase EC2.7.7.12), GalU (UDP-glucose pyrophosphorylase EC2.7.7.9), PPA (inorganic pyrophosphatase EC3.6.1.1), UMK (UMP kinase EC2.7.4.14), NDK (nucleotide diphosphate kinase EC2.7.4.6), PpK (polyphosphate kinase EC2.7.4.1)...

Fig. 20.5 The Leloir pathway of galactose metabolism and the uridine diphosphate (UDP) glucose pyrophosphorylase pathway. Gaik, galactokinase gait, galactose 1-phosphate uridyltrans-ferase gale, UDP-galactose 4-epimerase hex, hexokinase pgm, phosphoglucomutase Ugp, UDP-glucose pyrophosphorylase...

Scheme 17. 1) phosphoglucomutase 2) UDP-glucose pyrophosphorylase 3) UDP-galactose-4 epimerase 4) P(l-4)galacfosyl transferase 5) phosphokinase. 

Newell and coworkers found that, during particular stages of fruit construction in Dictyostelium discoideum, four functionally related enzymes accumulated, reached characteristic levels of specific activity, and then disappeared partly or completely. These enzymes were UDP-d-glucose pyrophosphorylase, trehalose 6-phosphate synthetase, UDP-d-galactose 4-epimerase, and UDP-D-galactose polysaccharide n-galactosyl transferase. 

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